Nature manipulation like in Movie 4
I thought at the end of Movie 4, with the princess ''injecting'' her chakara into Naruto's resengan, could be a huge indication as to how Naruto could beat Pein without manipulating all the chakara elements himself.
His giant "sun'' rasengan could literally be as destructive and hot as the sun with Sasuske's ''great fireball.''
I believe that Gara will make a return, and show Naruto how to throw the rasengan like how he manipulates the sand. ie grinding rock with wind chakara, and using the wind to ''craddle'' the rasenshurrikan, like he makes the sand fly, maybe a tornado thing.
Its a given that Naruto and Sauske have to reconcile their differences. The greatest symbolism possible would be to have Naruto and Sauske work together, as opposed to Madara and the First/Fourths' past. Most likely in order to defeat a common enemy, being Madara. His actions led to both their familys' deaths, and that will unite N and S again. Most likely Madara will reveal his true purpose in the Uchiha anniliation, and to Naruto who his father was. When Naruto learns who his father is, it should be like opening the pandoras box for the enemy, and give him the willpower to overcome all odds.
How it will all go down... no idea.